Add NEWS entries about JIT in Jul ~ Dec

* Instance variables
  * Merge ivar guards on JIT https://github.com/ruby/ruby/commit/a69dd699ee630dd1086627dbca15a218a8538b6f https://github.com/ruby/ruby/commit/e4f7eee009ebe1f23ee3e5ea69ccd9ea1530bc6f
  * Prefer RB_OBJ_FROZEN_RAW https://github.com/ruby/ruby/commit/5611066e03fe73bdbb08cc46f79530c69975cf17
  * Skip checking ROBJECT_EMBED https://github.com/ruby/ruby/commit/81a8d1cf09d59f0d69143d7896545f849f580a4e
* Method inlining
  * Mark some Integer methods as inline https://github.com/ruby/ruby/commit/0703e014713ae92f4c8a2b31e385718dc2452eac
  * Allow inlining Integer#-@ and #~ https://github.com/ruby/ruby/commit/dbb4f1996939d0ce977e6b37579e28dd886428ff
  * Inline builtin struct aref https://github.com/ruby/ruby/commit/167d139487d67613bd02522e24476f06ffa137b7
  * Make Kernel#then, #yield_self, #frozen? builtin https://github.com/ruby/ruby/commit/24fa37d87a24dc932c1d778bcaf91204f5c12a76
  * (For future) Rewrite Kernel#tap with Ruby https://github.com/ruby/ruby/commit/f3a0d7a2035e9f5e0c70effd55732607e3def263
* Other optimizations
  * Inline constant references https://github.com/ruby/ruby/commit/53babf35ef5b643774636550ea23851e2607e076
  * Lazily move PC with RUBY_VM_CHECK_INTS https://github.com/ruby/ruby/commit/5d74894f2bc4a3a18aec952d946ead3d784cb4b4
  * Cache access to reg_cfp->self on JIT https://github.com/ruby/ruby/commit/d40983772966938828a28c6e89752a3e76447b9e
* JIT compaction
  * Shrink the blocking region for compile_compact_jit_code https://github.com/ruby/ruby/commit/ed8e552d4d2c825a3f780ac8bd898eaaca7c21e7
  * Stop leaving .c files for JIT compaction in /tmp https://github.com/ruby/ruby/commit/fa1250a506e9b6a1bcbf664f6b7b9c06e045d9b9
* GC of JIT-ed code
  * Run unload_units in the JIT worker thread https://github.com/ruby/ruby/commit/16dab6b69263ed9c816bc0283c8c1f2f95dc1027
  * Avoid unloading units which have enough total_calls https://github.com/ruby/ruby/commit/d80226e7bd801fcbccf71f19ba373b7baf71a49e
  * Throttle unload_units https://github.com/ruby/ruby/commit/122cd35939ddf8ef7bfa17ad75570c01d0cf06ab
  * Throttle JIT compaction https://github.com/ruby/ruby/commit/096f54428d8000cccce430022784cb0e7cd31cb4
* Compilation speed
  * Eliminate IVC sync between JIT and Ruby threads https://github.com/ruby/ruby/commit/0960f56a1d773c5417e9de729e159d346aec17ca
  * Lazily move units from active_units to stale_units https://github.com/ruby/ruby/commit/5d8f227d0edd3c542fcac465eb82005a5f852d34

Please see https://github.com/ruby/ruby/commit/200c5f4075cb1d179c2eba5b30b5b0a500870f67 for other improvements in Jan ~ Jun.

1 files changed, 38 insertions, 9 deletions

diff --git a/NEWS.md b/NEWS.md
index eb1d191e67..3248109210 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -630,22 +630,51 @@ Excluding feature bug fixes.
 
 ### JIT
 
-* Native functions shared by multiple methods are deduplicated on JIT compaction.
+* Performance improvements of JIT-ed code
 
-* Decrease code size of hot paths by some optimizations and partitioning cold paths.
+    * Microarchitectural optimizations
 
-* Not only pure Ruby methods but also some C methods skip pushing a method frame.
+        * Native functions shared by multiple methods are deduplicated on JIT compaction.
 
-    * `Kernel#class`, `Integer#zero?`
+        * Decrease code size of hot paths by some optimizations and partitioning cold paths.
 
-* Always generate appropriate code for `==`, `nil?`, and `!` calls depending on
-  a receiver class.
+    * Instance variables
 
-* Optimize instance variable access in some core classes like Hash and their subclasses.
+        * Eliminate some redundant checks.
 
-* Eliminate VM register access on a method return.
+        * Skip checking a class and a object multiple times in a method when possible.
 
-* Optimize C method calls a little.
+        * Optimize accesses in some core classes like Hash and their subclasses.
+
+    * Method inlining support for some C methods
+
+        * `Kernel`: `#class`, `#frozen?`
+
+        * `Integer`: `#-@`, `#~`, `#abs`, `#bit_length`, `#even?`, `#integer?`, `#magnitude`,
+          `#odd?`, `#ord`, `#to_i`, `#to_int`, `#zero?`
+
+        * `Struct`: reader methods for 10th or later members
+
+    * Constant references are inlined.
+
+    * Always generate appropriate code for `==`, `nil?`, and `!` calls depending on
+      a receiver class.
+
+    * Reduce the number of VM register accesses on branches and method returns.
+
+    * Optimize C method calls a little.
+
+* Compilation process improvements
+
+    * It does not keep temporary files in /tmp anymore.
+
+    * Throttle GC and compaction of JIT-ed code.
+
+    * Avoid GC-ing JIT-ed code when not necessary.
+
+    * GC-ing JIT-ed code is executed in a background thread.
+
+    * Reduce the number of locks between Ruby and JIT threads.
 
 ## Static analysis